1. Field of the Invention
The present invention pertains to an image forming apparatus such as a printer or facsimile machine, and more particularly to the control when a malfunction occurs in the image forming apparatus.
2. Description of the Related Art
It is conventionally known that there are two types of problems and malfunctions that occur in an image forming apparatus: one comprises malfunctions that do not directly affect the image forming operation, such that image formation may be continued (indirect malfunctions), and the other comprises malfunctions that affect the image forming operation such that image formation cannot be continued (direct malfunctions). It is known that, in the case of an indirect malfunction, the image forming operation may be carried out by stopping the functions of the unit experiencing the malfunction and using the remaining units only. On the other hand, where a direct malfunction occurs, the image forming operation is immediately suspended.
The applicant has observed, however, that even in the case of a direct malfunction, there are cases where the image forming operation may be performed without affecting image performance or apparatus performance so long as prescribed conditions exist. For example, where the motor that rotates the toner bottle experiences a problem, although the supply of toner to the developing device will stop, so long as there is toner remaining inside the developing device, image forming operation may be continued until the toner inside the developing device has been consumed.
However, in a conventional image forming apparatus, when the malfunction in the motor is detected, the operation of the developing device is immediately stopped because normal toner supply is no longer available. This leads to immediate cessation of the image forming operation as well. Thus, conventional image forming apparatuses have the problem of a low operation rate because the image forming operation is suspended based on the detection of a malfunction that does not immediately affect the image forming operation.